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gerrit-public.fairphone.software / platform / system / libbase / 8a06da8b74a03f3d4af163007fbd9e24e7b08064
commit8a06da8b74a03f3d4af163007fbd9e24e7b08064[log] [tgz]
authorTom Cherry <tomcherry@google.com>Wed Apr 22 11:37:26 2020 -0700
committerTom Cherry <tomcherry@google.com>Wed Apr 22 13:12:11 2020 -0700
tree06ee04ed48c79d4063bbe068788446b2c3706006
parentcced25f47ea631c93fe07e864f9d81900e0824c9 [diff]
Remove thread safety from libbase logging / liblog

There are no libbase users that require thread safety for SetLogger,
SetAborter, or SetDefaultTag  and the equivalent liblog symbols are
unreleased, thus have effectively no users.

It is hard to imagine a scenario where a user would need to use these
functions in a multi-threaded program, and it is unreasonable for all
users to pay for thread safety for a vast minority of potential
scenarios. Thread safety implies less efficiency and necessarily means
that these functions are neither fork safe nor async-signal safe, and
we do have users who depend on those characteristics.

It is always possible for users of the non-thread safe versions of
these functions to build thread safe versions on top of them.  For
example, if a user needs a thread safe SetLogger(), they can use the
non-thread safe SetLogger at the start of their program to register a
logger that has its own lock and pointer to a logger function.

Bug: 119867234
Test: logging unit tests
Change-Id: I8afffec1a6957d3bda95502a4c59493e0c5049ce
1 file changed
tree: 06ee04ed48c79d4063bbe068788446b2c3706006
  1. include/
  2. tidy/
  3. .clang-format ⇨ ../.clang-format-2
  4. abi_compatibility.cpp
  5. Android.bp
  6. chrono_utils.cpp
  7. chrono_utils_test.cpp
  8. cmsg.cpp
  9. cmsg_test.cpp
  10. CPPLINT.cfg
  11. endian_test.cpp
  12. errors_test.cpp
  13. errors_unix.cpp
  14. errors_windows.cpp
  15. expected_test.cpp
  16. file.cpp
  17. file_test.cpp
  18. format_benchmark.cpp
  19. liblog_symbols.cpp
  20. liblog_symbols.h
  21. logging.cpp
  22. logging_test.cpp
  23. macros_test.cpp
  24. mapped_file.cpp
  25. mapped_file_test.cpp
  26. no_destructor_test.cpp
  27. OWNERS
  28. parsebool.cpp
  29. parsebool_test.cpp
  30. parsedouble_test.cpp
  31. parseint_test.cpp
  32. parsenetaddress.cpp
  33. parsenetaddress_test.cpp
  34. process.cpp
  35. process_test.cpp
  36. properties.cpp
  37. properties_test.cpp
  38. README.md
  39. result_test.cpp
  40. scopeguard_test.cpp
  41. stringprintf.cpp
  42. stringprintf_test.cpp
  43. strings.cpp
  44. strings_test.cpp
  45. test_main.cpp
  46. test_utils.cpp
  47. test_utils_test.cpp
  48. threads.cpp
  49. utf8.cpp
  50. utf8_test.cpp
README.md

libbase

Who is this library for?

This library is a collection of convenience functions to make common tasks easier and less error-prone.

In this context, "error-prone" covers both "hard to do correctly" and "hard to do with good performance", but as a general purpose library, libbase's primary focus is on making it easier to do things easily and correctly when a compromise has to be made between "simplest API" on the one hand and "fastest implementation" on the other. Though obviously the ideal is to have both.

Should my routine be added?

The intention is to cover the 80% use cases, not be all things to all users.

If you have a routine that's really useful in your project, congratulations. But that doesn't mean it should be here rather than just in your project.

The question for libbase is "should everyone be doing this?"/"does this make everyone's code cleaner/safer?". Historically we've considered the bar for inclusion to be "are there at least three unrelated projects that would be cleaned up by doing so".

If your routine is actually something from a future C++ standard (that isn't yet in libc++), or it's widely used in another library, that helps show that there's precedent. Being able to say "so-and-so has used this API for n years" is a good way to reduce concerns about API choices.

Any other restrictions?

Unlike most Android code, code in libbase has to build for Mac and Windows too.

Code here is also expected to have good test coverage.

By its nature, it's difficult to change libbase API. It's often best to start using your routine just in your project, and let it "graduate" after you're certain that the API is solid.